Real time tracking of borescope tip pose

The authors present a technique for the real-time tracking of borescope tip pose. While borescopes are used on a regular basis to inspect machinery for wear or damage, knowing the exact location of a borescope is difficult due to its flexibility. They present a technique for incremental borescope pose determination consisting of off-line feature extraction and on-line pose determination. The feature extraction precomputes from a CAD model of the object the features visible in a selected set of views. The on-line pose determination starts from a current pose estimate, determines the visible model features, projects them into a two-dimensional image coordinate system, matches each to the current borescope video image (without explicitly extracting features from this image), and uses the differences between the predicted and matched feature positions in a gradient descent technique to iteratively refine the pose estimate. The approach supports the mixed use of both matched feature positions and errors along the gradient within the pose determination. The on-line system is designed to execute at video frame rates, providing a continual indication of borescope tip pose.